Update docker image to go1.8rc2
Update docker image to go1.8rc2

CAT: #chore
REF: #2

eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim,eawsy/aws-lambda-go-shim